LeRobot v0.4.0 introduces substantial enhancements to open-source robotics learning, focusing on scalability, usability, and integration. The update includes the overhauled Datasets v3.0 with chunked episode formats and efficient video streaming, a new plugin system for seamless hardware integration, and support for LIBERO and Meta-World simulations. It also simplifies multi-GPU training and introduces new Vision-Language-Action models like PI0.5 and NVIDIA's GR00T N1.5, enhancing open-world generalization and complex task performance. Additionally, a new data processing pipeline using Processors facilitates efficient data management between robots and AI models. The release is complemented by a comprehensive open-source robot learning course and a hands-on modern robotics tutorial, aimed at making advanced robotics concepts and practical applications accessible to a broader audience.